As warm air rises, cold air falls. In large, high-bay buildings the effect is exaggerated, with much valuable warmth heading into the roof space where it is trapped, leading to cold zones at floor level. Faced with high-level heat stratification and increasing energy costs, what options are available for the project consultant and specifier?
In tall buildings, heat losses can be increased by about 20%, adding to the country’s carbon burden unless an adequate means of de-stratification is designed into any high bay heating system. One solution is to install high level de-stratification fans, forcing the air back down to lower levels, but installation and maintenance costs will be high, especially as working at height becomes more expensive.
An alternative, simple to install, economical and fuel efficient system has been developed that uses first physical principles to keep warm air gently circulating, maintaining constant comfort temperatures without the need for additional costly high level equipment. An air rotation heating system works in a completely different way from most other warm air heating systems. A high airflow, low air velocity unit positioned at floor level draws in cool air and discharges it at high level across the roof space. The units “rotate” the cool air normally located at floor level and mixes it with the warmer high level air causing it to fall and be drawn back down to low level by the constant air re-circulation.
The system has minimal operator involvement, being fully automatic, constantly modulating to maintain the temperature at a
pre-set level with no perceptible air movement.
In the event additional heat is required, the pre-mixed air passing through the unit is tempered via an indirect high efficiency gas fired heat exchanger. The burners are capable of a 4:1 modulation to ensure the discharge air is only slightly heated to maintain the space at exactly the right temperature without excess heat stratification or localised overheating. Heat is distributed evenly, both horizontally and vertically. All this is achieved without costly ductwork or de-stratification fans, reducing installation costs to a minimum.
The system is economical and runs on natural gas or LPG. A recent temperature monitoring exercise in a 12m high, 16,000m2 warehouse, serviced by three air rotation units showed only a 2°C temperature gradient between 1.5m and 11.5m levels, proving the effectiveness of the system.
A custom designed system requires few heaters and siting them at floor level reduces maintenance requirements. Installation is fast and simple. Since the units incorporate robust, low noise, heavy duty fans running at relatively low speeds life expectancy is considerably increased. This further reduces overall life cycle costs.
Air rotation makes simple work of keeping large high-bay buildings warm while providing the ideal solution for energy and environmentally conscious consultants, specifiers and building owners. Reliability, quality, financial return, long-term energy savings and reduced carbon emissions – all in one straightforward system.
Paul Fox is UK sales manager at Ambirad